Cup assemblies for use by infants often comprise a spout or nipple, and include a valve which can be opened via the application of negative pressure by suction on the spout or nipple by the infant. Typically, a flexible valve member blocks fluid flow in a rest position, and the application of negative pressure by the infant (i.e. sucking) causes the flexible valve member to flex, move or invert to allow fluid flow. However, such a valve arrangement can have several disadvantages. Suction operated valves are often subject to leaks; as the valve must be opened by the application of negative pressure by an infant, the valve must necessarily have a relatively small sealing force and can be easily inadvertently opened. For example, liquid can impact the valve member from within the cup and act to push the flexible part of the valve open, especially when the cup is vigorously shaken, inverted, or when the cup is accidentally dropped. Furthermore, the infant is restricted to drinking from the spout. This requires the infant to hold the cup in a certain orientation. The functionality offered by such a cup does not prepare the infant for using ‘open ended’ cups, from which the infant will be expected to drink as an adult.
It has been appreciated that a drinking cup assembly having a valve which is operated by direct contact pressure from the lips of an infant can mitigate some of the above detailed problems. This arrangement not only allows a stronger seal to be provided, but can also be designed such that the infant can drink from any point around a rim of the cup. Known lip-openable valve assemblies typically comprise a disc-shaped cap or actuator located above a valve arrangement with a high degree of circular symmetry. A central circular valve member is anchored at a central cylindrical axis of the cup, and in a rest position the circular valve member is biased to block apertures in the valve assembly, or seal against an inner surface of the circumference of the cup, in such a manner that fluid flow from the cup is prevented. Biasing of the valve arrangement is typically provided by biasing means located at the central anchoring location of the circular valve member. When a user wishes to drink from the cup, he or she pushes an upper surface of the cap downwards with their lips. The cap is rigidly attached to the circular valve member, and therefore this movement causes the circular valve member to pivot or bend about its central anchoring location, causing the apertures to be unblocked or a fluid flow path to be otherwise created. However such arrangements tend to provide poor seals and/or are difficult to actuate, and additionally prove to leak when shaken.
EP1123027B1 describes a drinking container of this general type having a lid with a valve which is openable by a user's lips.
The present invention seeks to address these and other disadvantages encountered in the prior art by providing an improved valve assembly for a drinking cup.